I've got a TC Powercore Mk1 sitting in my Single 1.6 G5, and it seems that every now and then it'll go through a spout of not being recognized. Every time I look in the apple system profiler it looks the same, but the TC software will sometimes recognize the card, and sometimes it will say "Unknown device"

It seems that it'll work well for a while (couple of days, with any amount of restarts), and then it won't work for a couple of days (any amount of restarts doesn't help), and then it'll magically work again when coming back to it later.

Might I have a broken Powercore card? Other thoughts are that it might be in conflict with the UAD-1 card I have installed in the slot next to it, anyone had issues with that?

i used to get that with an old Asus P4 board regularly, it was a known problem.I think the work around was to set an extra check of anykind in the bios (memory/HD etc)just to slow down the boot process to give it time to recognise the card. Don't know how you'd do that with a mac though.